The determination of losses on the transmission input side, particularly in the case of automatic motor vehicle transmissions having unsynchronized interlocking shifting elements, is of interest since in these, to carry out shifting operations rotational speeds in the area of the unsynchronized shifting element concerned must be synchronized at least as much as possible, so that when the shifting element is actuated an interlocked coupling of corresponding transmission components can be formed in as problem-free a manner as possible. The more accurately drag torques in the area of the transmission input are known in such cases, the more precisely a transmission control unit can adjust the respective rotational speed relationships. Consequently, by determining drag torques in the area on the drive input side the comfort when carrying out shifting operations that involve unsynchronized shifting elements can be improved substantially.
DE 10 2011 016 576 A1 describes a method for determining drag torques of two friction clutches which, being combined in a dual clutch, are each part of a dual-clutch transmission. In this case each friction clutch is associated with one of the downstream partial transmissions. In the method the drag torque of the clutch of whichever partial transmission is operating passively can be determined during operation, while the friction clutch of the respective partial transmission that is operating actively is operated with a controlled amount of slip.